Production of hard, wear-resisting printing surfaces



Patented June 12, 1928.

UNITED STATES PATENT OFFICE.

KEVIE W, SCHWARTZ, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO UNITED CHROMIUM, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

PRODUCTION OF HARD, WEAR-RESISTIN G PRINTING SURFACES.

No Drawing.

The invention relates to the production of hard, Wear resisting surfaces for printing media, such as rolls, plates and the like, and comprises the formation of the impressions, to be printed, on a metallic body or base and electrically coating the impression surface with chromium or chromium alloys.

In the art of printing upon paper, textile fabrics and similar media, by means of engraved, impressed or embossed rolls or plates, it has been practically impossible to obtain impression surfaces of sufficient hardness and durability to long withstand the attritive forces involved in the use of the means for removing surplus ink, such means being either in the form of steel doctor knives, manual or mechanical wipers or the like. It has been sought to remedy these defects by case hardening the printing faces of steel rolls and dies and by alloying similar rolls or dies made of copper, but these various methods have not been entirely satisfactory, because they either fail to produce the desired surface hardness and consequent durability of the printing media, or the latter are unable to withstand high temperatures or the corrosive action of chemicals or atmospheric conditions. It is the object of the instant invention to correct or obviate all of these objectionable characteristics of the printing rolls or plates by providing the same with a coating that is at once tough, hard and resistant to wear and corrosion, so that the effective life of the printing media will be materially prolonged.

While the invention is applicable to printing surfaces or media generally, it finds its widest application to rolls or plates of copper or steel, either engraved, etched or embossed with the impression or design to be printed, and a specific description of the necessary operations as applied to a copper roll, sue 1 as commonly employed in textile printing, will afford a sufficient exemplitication of the invention to enable those skilled in the art to practice the same.

The roll of copper, or similar material, is highly polished and buffed previous to engraving. After the desired design or impression has been engraved thereon and due care taken to preserve the high polish and smoothness of the original finish of the surface which is not engraved, the roll is Application filed August 5, 1925. Serial No. 48,306.

mounted on suitable contacts and electrolytically cleaned in an alkaline bath for the purpose of removing all dirt, grease and foreign matter. After the engraved roll has been thoroughly cleansed in this manner, it s removed from the cleansing device, rinsed in clean water and dipped in a solution of sodium cyanide for the purpose of removing any existing film of oxide which may have formed during the cleaning operation. After the cyanide dip, the roll is again rinsed in clean water and is ready to be applied to the chromium plating bath, which constitutes the electrolyte of a suitable electrolytic cell. The preferred electrolyte consists of 325 grams of chromic acid per liter of water, 12 grams of chromium hydroxide per liter of water and 21 grams of chromium sulphate per liter of water- The electrolytic cell is operated at a current density of from 100 to 150 amperes per square foot of surfaces and a voltage of from 5 to 10, the operation to be carried out at a temperature of from 25 degrees to 45 degrees centigrade. The thickness of the chromium deposit necessarily varies with the design and the character of the metal receiving the coating and may be anywhere from .0001 to .001 or more. Such a coating preserves the outlines and impressions of the design on the printing media implicitly, so that it is unnecessary to go over the impressions or outlines on the printing surface. After the coating operation has been completed and the electrolytic deposit of chromium of the desired thickness has been obtained, the roll is removed from the electrolytic cell, thoroughly rinsed, and dried and is then ready for immediate use in the press.

Extensive tests of engraved copper and steel rolls plated with chromium or chromium alloys, in the manner set forth, show that the life of such rolls, under normal operations, is greatly increased. Furthermore, as soon as the roll shows signs of wear so as to develop imperfections in the printing, the hard chromium surface may be d15- solved and a new surface deposit of chromium applied in the manner as described. The dissolution of the chromium deposit may be effected in several ways. It may be dissolved by inunersing the mold in a hydrochloric acid solution, or by placing the plated roll in a chromium plating bath as III) an anode, thereby causing the chromium to be taken up in solution by the electrolyte. Also, should it be found desirable to turn the roll down for the purpose of placing a new desi n thereon, the chromium surface may be issolved in either of the manners just indicated, after which the surface of the roll may be turned off in the same manner as now practiced. Of course, the same conditions would apply to plates or dies of copper, steel or the like and the latter ma be provided with the electrolytically deposited coating of chromium or chromium alloys in substantially the same manner, and the coating may be removed, when necessary, by the same modes applied to the rolls.

The process, as described, is, in no sense, limited to rolls, plates, dies or similar printing media of copper and steel, but may be applied with e ual advantage to printing media made of rass,-nickel or other metals capable of taking and retaining the lines or markings definin the designs or outlines to be printed. T e invention is also especially applicable to steel rolls, plates or dies which heretofore have been case hardened, as the application of the electrolytic coating of chromium will completely obviate the necessity of case hardening or similarly treating the surface of such steel printing media.

As indicated, the surface hardening produced by the deposit of chromium or chromium alloys has proven of great value in promoting the durability and wearing qualities for continuous use in printing linoleum, oilcloth, chinaware, paper, textile fabrics and the like, as the very hard deposit of chromium or chromium alloy successfully resists the abrasive effects of the ink removing devices and the ordinary wear and tear of operation due to contact with the surfaces to which the printing is to be applied.

\Vhat I claim is:

1. As a new article of manufacture, a printing medium comprising an unhardened steel body bearing the design to be printed, and a coacting of electrolytic chromium on its printing surface.

2. A fine engraving plate, comprising an unhardened steel body bearing the design of a fine engraving, and a coating of electrolytic chromium on its printing surface.

3. A method of manufacturing printing media, comprising forming the design to be pqignted in or on unhardened steel, and the'rea ter electro-depositing chromium upon the unhardened steel surface bearing the design.

In testimony whereof I affix my signature.

KEVIE W. SCHWARTZ.

CERTIFICATE OF CORRECTION.

h m no. 1,673,779.

Granted June 12, 1928, to

KEVIE W. SCHWARTZ.

It is hereby certified that error appears in the printed specification in the above numbered patent requiring correction as follows: Page 2. line 49, claim 1, for the word "coacting" read "coating"; and that said Letters Patent should be read with thie'correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 24th day of July, A. D. 1928.

WM. A. Kinnln, Acting Commissioner of Patente.

an anode, thereby causing the chromium to be taken up in solution by the electrolyte. Also, should it be found desirable to turn the roll down for the purpose of placing a new desi n thereon, the chromium surface may be issolved in either of the manners just indicated, after which the surface of the roll may be turned off in the same manner as now practiced. Of course, the same conditions would apply to plates or dies of copper, steel or the like and the latter ma be provided with the electrolytically deposited coating of chromium or chromium alloys in substantially the same manner, and the coating may be removed, when necessary, by the same modes applied to the rolls.

The process, as described, is, in no sense, limited to rolls, plates, dies or similar printing media of copper and steel, but may be applied with e ual advantage to printing media made of rass,-nickel or other metals capable of taking and retaining the lines or markings definin the designs or outlines to be printed. T e invention is also especially applicable to steel rolls, plates or dies which heretofore have been case hardened, as the application of the electrolytic coating of chromium will completely obviate the necessity of case hardening or similarly treating the surface of such steel printing media.

As indicated, the surface hardening produced by the deposit of chromium or chromium alloys has proven of great value in promoting the durability and wearing qualities for continuous use in printing linoleum, oilcloth, chinaware, paper, textile fabrics and the like, as the very hard deposit of chromium or chromium alloy successfully resists the abrasive effects of the ink removing devices and the ordinary wear and tear of operation due to contact with the surfaces to which the printing is to be applied.

\Vhat I claim is:

1. As a new article of manufacture, a printing medium comprising an unhardened steel body bearing the design to be printed, and a coacting of electrolytic chromium on its printing surface.

2. A fine engraving plate, comprising an unhardened steel body bearing the design of a fine engraving, and a coating of electrolytic chromium on its printing surface.

3. A method of manufacturing printing media, comprising forming the design to be pqignted in or on unhardened steel, and the'rea ter electro-depositing chromium upon the unhardened steel surface bearing the design.

In testimony whereof I affix my signature.

KEVIE W. SCHWARTZ.

CERTIFICATE OF CORRECTION.

h m no. 1,673,779.

Granted June 12, 1928, to

KEVIE W. SCHWARTZ.

It is hereby certified that error appears in the printed specification in the above numbered patent requiring correction as follows: Page 2. line 49, claim 1, for the word "coacting" read "coating"; and that said Letters Patent should be read with thie'correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 24th day of July, A. D. 1928.

WM. A. Kinnln, Acting Commissioner of Patente. 

